MECHANICAL
FlowMeasLab_and_Worksheet.pdf

# B estimate the uncertainty in the p s tube velocity

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b. Estimate the uncertainty in the P-S tube velocity readings based on a the standard deviations and manufacturer's bias in dynamic pressure measurement, reasonable errors in tube position and angle (Figure 6), and variations in the room conditions. 3. Calculate the volumetric flow in the duct by integrating the velocities found from each of the two pitot traverses over the duct area. You will get two values of Q . Compare the integration of each traverse with the volumetric flow found from the orifice. 4. Plot the duct mean static pressure as a function of distance from the fan outlet. Identify in detail the pressure features that relate to the recoverable orifice pressure drop, the unrecoverable orifice pressure drop and the friction pressure drop. 5. Use Figure 5 and the duct Reynolds number to calculate the friction pressure drop expected per unit length of the duct. How does this compare to the measured change in duct mean static pressure observed downstream of the orifice. 6. Plot the duct non-recoverable static pressure drop, measured from the difference in the static probe readings, against the duct volumetric flow rate obtained from the orifice pressure drop measurements in Steps 2b,c. You'll need to calculate the orifice flow from the orifice mean pressure drop at each of the flowrates. Check Re for each flowrate to be sure the orifice coefficient is correct. Show that this plot follows a line of the form (VA ORF ) 2 = C( P N-R ) and then evaluate C.

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ME 4600:483 Lab Notes Revised 11/16/2015 Flow Measurement Page 11 of 18 VI. References 1. Theory and Design for Mechanical Measurements. R.S. Figliola and D.E. Beasley, Wiley, (1991). 2. Fluid Mechanics . F.M. White, McGraw Hill, (1979). 3. Fundamentals of Engineering Thermodynamics . M. J. Moran and H. N. Shapiro, Wiley, (1988). Figure 1a. Schematic of the installation of a Pitot-static probe and a metered orifice plate.
ME 4600:483 Lab Notes Revised 11/16/2015 Flow Measurement Page 12 of 18 Figure 1b. Detail of the velocities, pressures, and flow patterns through a generalized Bernoulli obstruction metered orifice (White, 1979). Figure 2a. Graph showing the variation of Flow coefficient with Reynold's number.

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ME 4600:483 Lab Notes Revised 11/16/2015 Flow Measurement Page 13 of 18 Figure 2b. Graph showing the variation of discharge coefficient with Reynold's number (White, 1979).
ME 4600:483 Lab Notes Revised 11/16/2015 Flow Measurement Page 14 of 18

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ME 4600:483 Lab Notes Revised 11/16/2015 Flow Measurement Page 15 of 18 Figure 4. The 24 equal area sections of the experimental circular duct. Figure 6. The effect of Pitot-Static tube yaw angle of measurements of stagnation and static pressure (White, 1979).
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